In Python 2 StringIO could accept either Unicode or 8-bit strings.
Similar change made for HttpUrl:
06fdd78f9 ("Python3: fix TypeError in HttpUrl.read_content()",
2019-09-15)
Non-existent FtpUrl.max_size introduced in:
7b34be590 ("Introduce check plugins, use Python requests for http/s
connections, and some code cleanups and improvements.", 2014-03-01)
Additional self.direct() not added in:
f107092a8 ("Fix handling of user/password info in URLs.", 2012-06-10)
4b06485a05